BASIC RADIO DAY 1

Answer 1

C= LAMBDA/FREQUENCY

Question 2

DOPPLER PRINCIPLE

Answer 2

CONVERGING: received frequency increses
DRIVING : received frequency decreases

Question 3

In phase angle

Answer 3

Difference is 0 and the amplitutde adds up

Answer 4

VLF 3-300 KHZ
LF 30-300
MF 300-3000

HF 3-30MHZ

Question 5

MODULATION

Answer 5

Process of impressing and transporting information by radio

Question 6

Pulse modul

Question 7

Amplitude

Answer 7

You keep the freequency same,amplitutde changes

Question 8

Frequency

Answer 8

Keep same amplitutde changes the frequency

Question 9

Phase modulation

Answer 9

Phase is flipped ,but the frequency and amplitude changes

Question 10

Pulse modulation

Answer 10

Power contianed within a single pulse

Question 11

Ampkitude modulation

Answer 11

The info is impresses onto the carried wave by altering the amplitude pf the carrier

Question 12

Frequncy modulation

Answer 12

Altering the freqeuncy of the carrier

Question 13

Am modulation

Answer 13

Is susceptible to noise ,because it cant filter the noise

Question 14

Frequency modulation

Answer 14

Amplitude says the same.
Less susceptible to noise
More effiecient ,less power

Noise in genral changes the amplitude and the frequency,thats why fm can detect noise,bc if ampitude changes it ignores bc amlitude should say the say in FM

Question 15

Phase modulation

Answer 15

Used in GPS
Requires comples demmodulator
Reverse phase of carrier

Question 16

Sidebands

Answer 16

When wave is modulated ,the result consists of the carrier frequency plus upper and lower sidebands
All modulations produce sidebands

Question 17

~signals with two sidebands plus the carrier ,occupy a large bandwith
~removing one sideband increses efficiency
~HF and volmet use single sideband transmission

Answer 17

You can remove the carrier o r one of the side bands to make the signal more efficint

Question 18

SCW (suppressed carrier wave)

Answer 18

We can suppreses the carrier wave as well making it even more effiecnt.

If ypu take awa ythe carrier the ssignal is not good,so we need to add the carrier at the reciever,this requires a beat requncy oscillator (BFO) at the reciever to re insert the removed carrier wave frequcny

Question 19

Signal classification

Answer 19

~first letter: type of modulation of the carrier wave
~second: nature of thrsignal carrier
~third: type of info being transmitted

N0N: carrier wihtout modualtion ,used by NDBs
A1A:carrier with key modulation

Question 20

Antenna

Answer 20

Is an elcetric device which converts electric pwer into radio waves and vicevers
Ac current

Question 21

Electromagnetic waves

Answer 21

~oscillating electric field (E)
~oscillating magentic (H) field
~perpendicular to each other
~in phase with each other
~

Question 22

Polar diagrapms

Question 23

Polarisation

Answer 23

~describes the plane of oscillation of the electric component of wave with Regard to its direction of propagation
~determined by the orientation of the antenna

~linear ,vertical or horiznatal

~circular &raquo_space;>requires helical antenna
~elliptical&raquo_space;> requires helical antenna

~receivers antenna must be aligned same way as the transmitter to properly receive the transmitted signal

Question 24

Dipole antenna

Answer 24

~simples type of antenna
~wire of length equal to 1/2 wavelentgh
~omnidirectional
~prodices a cone of confusion overhead

Question 25

Loop antenna

Answer 25

~good at direction finsding (directional ) ~used in ADF equip ~looks for the null postions ~required a second sense antenna to elimiate one of the nulls Looks for differential voltage untill is 0

Question 26

Paqrabolic antenna

Answer 26

~good at amplifying weak signals ‘~used in older weather radar ~highly direcrtional

Question 27

Sloteed planar array antenna

Answer 27

~used in moder weather radr ~highle directrional ~sereis of slots which are scanned electronically ~more eff. Than a parabolic antenna.drastically reduces side lobes concentrtating energy into the main beam

Question 28

Helical antenna

Answer 28

Two types ~omnidirectional ,normal mode ,VHF adn COMMS ~directional ,axial mode ,GPS Produces a circular /elliptical plane of polarsation

Question 29

Antenna shadowiin

Answer 29

Is always refeared to a/c parts Ex. While in a turn it could shadow the antenna

Question 30

Reflection

Answer 30

An abrupt change in direciton of wave when it hits a surface. Caused by terrain ,builidng ,other a/c ,water droptlets

Question 31

Refraction

Answer 31

A change in direction of wave caused by change in progagation speed when moving from one medium to another

Question 32

Diffraction

Answer 32

Bending of waves around objects or through apertures. Describes the tendency of some waves to follow eartg curvature

Question 33

Factors affecting propagation

Answer 33

~absorption: the transfer of waves energy to the matter it has encoutered ~attenuation:gradual loss of energy a wave propartagtion through a medium ~multi path propagattion: wehn one signal with a single point and the time of transmission is refelcetd from surfaces between the transmittter and receiver

Question 34

Superpositon

Answer 34

Combination of two or more similar waves

Question 35

Interfernce

Answer 35

The result of superpostion of two waves

Question 36

Fading

Answer 36

Interference of singal rsulting in changes in signal strength and polarisation .caused by multi path ,weather

Question 37

Static interfence

Answer 37

Lectricl discharge,thunderstoms Man made vhf

Question 38

Wave propagation

Answer 38

~space wave,anything is higher than VHF HF ~ground waves ,trvels along the surface of the earth ~sky waves, refrected by the layers of theionoesphere( VLF,LF,MF,HF) MF ,possibile sky wave at night

Question 39

Ionosphere

Answer 39

Radio waves passing through inosphere layers are attenuated ~lower frequencies expereinces less attenuation

Question 40

Critacl angle

Answer 40

Is the first sky waves that returns back

Question 41

Dead space

Answer 41

Distance betweeen the limit of the sufaec wa